There are a number of collapsible, articulated frames on the market today, comprised of individual sections connected together, the frame--and each section thereof--movable between a collapsed configuration and a stable erect self-locking configuration. A typical such frame is shown in U.S. Pat. No. 4,276,726. While such frames are very functional, in order to support relatively heavy graphics, or other articles, rather than merely conventional thin Lexan graphic panels (or the like), it is desirable to use accessory brace rods, or like structures, which--after erection of the frame--are added to the structure to hold it in place.
According to the present invention, a collapsible, articulated structural section--and frame formed by a plurality of such sections--is provided which does not require separate accessory brace rods, or the like, yet provides stability that is comparable to that provided when such accessory rods are used. This is accomplished according to the present invention by providing--instead of a self-locking action, which is present in prior art portable exhibit frames--a manually actuated locking component which positively prevents collapse of the lock even when relatively heavy articles, panels and the like are supported by the frame. The manual locks increase set-up time only a small amount compared to conventional self-locking frames, and do not really increase set-up time at all compared to conventional frames when accessory brace rods, and the like are used, while eliminating the need for carrying the accessory brace rods around, making sure that they are detached before collapse, etc.
According to the present invention a first plurality of pivot means are disposed to be spaced from each other and generally in a first plane in the erect configuration, and to be substantially adjacent each other in the collapsed configuration. A second plurality of pivot means are also disposed to be spaced from each other and generally in a second plane in the erect configuration and to be substantially adjacent each other in the collapsed configuration. A plurality of pivotally interconnected side links are provided for connecting the first plurality of pivot means with the second plurality of pivot means, each of the side links being connected with one of the first plurality of pivot means and one of the second plurality of pivot means. First and second face pivot means are provided, and a first and a second plurality of face links, each of the first plurality of face links connected with the first face pivot means and with one of the first pivot means, and each of the second plurality of face links connected with the second face pivot means and one of the second pivot means.
Unique to the invention, each of the first plurality of face links crosses, but is unconnected to, one of the second plurality of face links (the first face pivot means is located closer to the second pivot means than it is to the first pivot means when the section is in the collapsed configuration). A first locking component is associated with the first pivot means and a second locking component is associated with the second pivot means, the first and second locking components comprising means--upon manual actuation--for holding the first and second face pivot means adjacent each other and to thereby hold the structural section in its stable erect configuration. A structural section is usually provided in combination with a plurality of substantially identical structural sections, with adjacent structural sections sharing some common first and second pivot means, and a common pair of side links, to provide a complete and portable display frame. Graphics are preferably attached to the display frame in the manner illustrated in U.S. Pat. No. 4,471,548 (the disclosure of which is hereby incorporated by reference herein).
A particularly advantageous, simple, and effective manually actuated locking structure for use in the structural section according to the present invention comprises a first locking component comprising means defining a through-extending opening in the first face pivot means, and a second locking component comprising a central shaft with a rotatable locking member. The central shaft of the second locking component extends from the second face pivot means towards the first face pivot means and has a free end on a portion thereof remote from the second face pivot means, the free end including a shaft termination portion dimensioned to fit in the first face pivot means opening. Preferably both the opening and the shaft end terminating portion are oval. The rotatable locking member is on the end of the shaft terminating portion and is mounted to the shaft by means providing rotation thereof from a first position in-line with the shaft end termination so that it can pass through the first face pivot means opening, to a second position not in-line wit the shaft end termination so that the locking member engages the first face pivot means on the opposite end thereof from the second face pivot means. Preferably the rotatable locking member is held in a detent position in both the first and second positions thereof, the second position being 90.degree. from the first position.
In a commercial frame produced according to the present invention, there usually will be four first pivot means, four second pivot means, eight side links, four first face links, and four second face links for each section, with adjacent structural sections sharing two common first pivot means, two common second pivot means, and a common pair of side links.
It is the primary object of the present invention to provide a simple, yet stable, structural section, and lockable display frame constructed from such a structural section. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.